Evapotranspiration losses for pepper under plastic mulch and shallow water table conditions

Use of literature crop coefficient (Kc) values for quantifying evapotranspiration (ETc) under non-standard conditions such as plastic mulch, shallow water table, and sub-tropical conditions can lead to inaccurate ETc estimates. A 5-year experiment was conducted for fall crop growing seasons in south Florida to quantity bi-weekly ETc and Kc for bell pepper grown under shallow water table and plastic mulch environments using large drainage lysimeters. The ETc values varied from 205 to 320 mm with a seasonal average of 267 mm. Average Kc values for bell pepper for development, mid-season, and late stages were 1.05, 1.21, and 1.28, respectively. Higher than literature initial Kc values were due to rainfall and use of sub-irrigation system to maintain artificially high water table which results in high soil moisture in the bare soil area—such high moisture results in high evaporation. The Kc values from this study were statistically higher than literature values. Use of literature Kc values resulted in underestimating ETc by 27–37%. The Kc values would provide improved estimates of sub-irrigated pepper ETc in subtropical Florida and elsewhere with similar environment.